Liquid-to-liquid heat exchanger

ABSTRACT

A liquid-to-liquid heat exchanger adapted especially for use with an automotive vehicle radiator assembly for transferring heat from automatic power transmission fluid to the engine liquid coolant comprising a pair of cylindrical tubes adapted to be positioned in coaxial disposition within the engine radiator heater and a helical turbulator positioned within an annular space defined by the cylindrical tubes, said turbulator comprising a rolled strip with a channel cross-section, said strip being wound about the axis of the heat exchanger to form a continuous helical flow channel, thus increasing the turbulence in the field flow path for the transmission oil.

United States Patent 1191 afillfillll 1451 Aug. 27, 1974LlQUlD-TO-LIQUID HEAT EXCHANGER 2,188,060 5/1938 Stone et a1 165/1842,752,128 6/1956 Dedo 165/155 [75] Inventor- 31 Rams", Westland,3,083,662 4/1963 Zeidler 165/155 x [73] Assignee: Ford Motor Company,Dearborn, P 'y EXami'leFCharleS Myhre Mi h Assistant Examiner.TheophilW. Streule, Jr. Attorney, Agent, or FirmDonald J. Harrington; Keith [22]Filed. June 2, 1972 L Zerschling [21] Appl. No.: 259,095

Related US. Application Data t I h t h CT d t d n v 1qu1 o-1qu1 ea excanger a ap e espec1a y [63] sggl gglfi of 131306 Apnl for use with anautomotive vehicle radiator assembly for transferring heat fromautomatic power transmis- 52 fluld to the engme hqud coolant comprisinga E H 8 i i g i g pan of cylindrical tubes adapted to be positioned in[58] i 183 l86 coaxial disposition within the engine radiator heater165/141 153 and a helical turbulator positioned within an annular spacedefined by the cylindrical tubes, said turbulator lled strip with achannel cross-section [5 6] References Cited cQmpns.mg m

said strip being wound about the ax1s of the heat ex- UNITED STATESPATENTS changer to form a continuous helical flow channel, I g l r -fithus increasing the turbulence in the field flow path aglesc 2,016,74610/1935 Ireland 165/75 for the transmlsslo? O1] 2,059,992 11/1936 Gould165/154 1 m, 8 aw ng igur s 16 h n h m i I 1 l 1,,J:: --*1: t 2 1 2 ,2 TT: I r: :::::1. 7 :1\\L

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I LIQUID-TO-LIQUID HEAT EXCHANGER REFERENCE TO RELATED DISCLOSUREGENERAL DESCRIPTION OF THE INVENTION The heat exchanger construction ofmy invention is adapted to be used for cooling oil used with anautomatic transmission in an automotive vehicle driveline. Suchtransmissions usually include a hydrokinetic torque converter whichmultiplies engine torque before it is distributed to transmissiongearing. The inherent slip in the torque converter causes a horsepowerloss which results in heating of the transmission oil. It is necessaryin arrangements of this type to circulate the oil continuously throughthe converter and through an oil cooler in order to maintain astabilized temperature during operation of the driveline under power.

The transmission oil cooler usually is situated in the lower radiatortank for the liquid-to-air heat exchanger or radiator used for thecooling of the engine coolant for the internal combustion engine. Thecoolant is circulated through a cooling jacket within the engine blockof the internal combustion engine. It is circulated also through thevehicle radiator located in the moving ambient air stream.

I am aware of several transmission oil cooler constructions inarrangements of this type, including the construction shown in US. Pat.Nos. 3,116,541 and 3,265,127. Each of these prior art constructionsincludes a so-called turbulator located between an inner and outer heatexchanger shell of generally tubular construction. The turbulator causesturbulence in the fluid flow path for the transmission oil that iscirculated through the transmission cooler in order to assist in heattransfer from one liquid medium to the other.

It is a principal feature of my invention to improve upon the heattransfer characteristics of heat exchangers of the type presently usedin the automotive industry by increasing the effective length of thefluid flow path as the fluid passes through the oil cooler. This lengthof the path increases the time during which the heated transmission oilis exposed to the cooled surfaces of the heat exchanger constructionthat are in contact with the liquid coolant in the engine radiator. Itis possible to reduce the effective size and to change the shape anddimensions of the transmission oil cooler to meet design and spacelimitations without adversely affecting the ability of the heatexchanger to maintain a stabilized temperature for the transmission oilat the desired operating temperature level. The improved performance ofmy heat exchanger is achieved by using a simplified construction thatlends itself to simplified manufacturing techniques. My improved heatexchanger construction includes inner and outer shells and a centrallydisposed turbulator that is comprised of a continuous rolled ribbon. Achannel is rolled by means of a suitable rolling die which forms theribbon along its length. The dies may be designed so that curling of therolled ribbon stock takes place as the channel cross-section is formed.The rolled ribbon may be coiled into a cylinder and assembled betweenthe inner and outer cooler shells, the ends of which may be sealed bywelding. Suitable fluid fittings then may be secured to the outermostshell to accommodate transfer of transmission oil through the helicalfluid flow path defined by the turbulator and the cooperating coolershells.

The length of the fluid flow path through the turbula-.

tor can be varied simply by varying the width of the ribbon.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING FIG. 1 shows a sideelevation view partly in crosssection of my improved heat exchangerassembly;

FIG. 2 is a cross-sectional view taken along the plane of section line22 of FIG. 1;

FIG. 3 is a side elevation view of the turbulator element used in theassembly of FIG. 1;

FIG. 4 is a cross-sectional view of the turbulator shown in FIG. 3;

FIG. 5 is a partial view of an unwrapped section of the ribbon stockused and formed in a turbulator of FIGS. 3 and 4.

FIG. 6 is a detail view showing a modified turbulator as it would appearin a wrapped condition following assembly.

FIG. 7 is a cross-sectional view taken along the plane of line 7-7 ofFIG. 6.

FIG. 8 shows a side elevation view partly in crosssection showing themodified turbulator of FIGS. 6 and 7 therein.

PARTICULAR DESCRIPTION OF THE INVENTION Numeral 10 in FIGS. 1 and 2designates a cylindrical outer shell for the heat exchanger of myinvention. It surrounds the cylindrical shell 12. The ends of shell 12are formed with an enlarged diameter section, as indicated at 16 and 18.The sections 116 and 18 engage the inner surface of the shell 10 and itmay be secured to the shell 10 by welding.

The shells l0 and 12 form an annular space 20 extending from one end ofthe assembly to the other. A fluid inlet fitting 22 surrounds an inletopening 24 formed in the shell 10.

Fitting 22 is threaded at 26 to permit a connection with a fluidtransmission line extending to the automatic transmission.

A fitting 28, which is similar to the fitting 22, is formed in the shell10 at the opposite end of the assembly shown in FIG. 1. It serves as anoutlet flow passage for the transmission oil circulated. through theassembly.

Positioned within the annular space defined by the shells 10 and 12 isthe turbulator shown in FIGS. 3 and 4. This comprises a coiled, rolledribbon of the type shown in FIG. 5. The ribbon is rolled to form achannel, the rolling dies having peripheries formed with thecross-sectional shape indicated in FIG. 4. After the rolling operationis completed, it is coiled in end-to-end relationship, as indicated inFIG. 4, so that its inside diameter is slightly larger than the outsidediameter of the shell 12. The height of the channel, which is indicatedby reference character 30, is slightly less than the radial thickness ofthe annular space between the shells l0 and 12.

Fluid entering the fluid fitting 2.2 is received within the fluidchannels of the turbulator. The fluid circulates in a helical paththrough the turbulator and then is received at the fitting 28 andreturned through a suitable fluid conduit to the transmission. Theassembly shown in FIG. 1 is placed in the lower header of the automotiveradiator so that the engine coolant circulates around the outer surfaceof the shell and over the inner surface of the shell 12.

The helical flow path produced by the turbulator increases the time ofexposure of the heated oil to the coolant in the radiator header,thereby improving the heat transfer capability of the cooler.

The helical flow path for the heated oil can be defined also by aturbulator of the type shown in FIG. 6. This includes a helical wire 32which would be wrapped about the shell 12 within the annular spacedefined by the shell 12 and the shell 10. It engages both shells anddefines a helical flow path. The wire 32 forms a seal which preventscross flow. Situated between the spaced windings of the wire 32 is aribbon or strip 34. The strip 34 is formed with indentations whichcomprise a series of alternately spaced undulations shown at 36 and at38. The undulations 36 are out of phase with respect to the undulations'38 so that apertures are formed between them. These apertures permitturbulant fluid flow through the heat exchanger as the fluid flowtraverses the helical circuit.

Having thus described a perferred form of my invention, what I claim anddesire to secure by US. Letters Patent is:

l. A liquid-to-liquid heat exchanger adapted especooled automotiveengine comprising a pair of heat exchanger shells of generally tubularconstruction, one shell being situated within the other in coaxialdisposition, said coolant circulating over the outer surface of theoutermost shell and over the inner surface of the innermost shell, saidshells defining therebetween an annular space, a turbulator constructionsituated in said annular space, a fluid fitting connected to theoutermost shell for receiving transmission oil and a fluid flow outletfitting connected to said outermost shell for receiving transmission oilcirculated through said cooler, the flow paths defined in part by saidfittings communicating with said annular space at axiallyspaced'locations, said turbulator construction registering with saidshells and forming therebetween a helical flow path for the fluid flowthat passes from one of said fittings to the other, said turbulatorconstruction comprising two parts, the first part being a helical wiresurrounding the innermost skill and engaging the adjacent shell surfacesto prevent crossflow from one point in the helical flow path to anotherin an axial direction, the geometric axis of the helical flow pathformed by said turbulator construction the second turbulatorconstruction being a turbulator ribbon having a plurality of undulationslocated between the helical wire and forming in said ribbon liquid flowopenings, said ribbon being wrapped around the innermost shell inhelical disposition whereby the flow path is generally helical and ischaracterized by localized turbulance.

1. A liquid-to-liquid heat exchanger adapted especially for use with an automatic power transmission mechanism for cooling oil circulated through the transmission mechanism and adapted to be mounted in liquid coolant within an air cooled radiator for a liquid-cooled automotive engine comprising a pair of heat exchanger shells of generally tubular construction, one shell being situated within the other in coaxial disposition, said coolant circulating over the outer surface of the outermost shell and over the inner surface of the innermost shell, said shells defining therebetween an annular space, a turbulator construction situated in said annular space, a fluid fitting connected to the outermost shell for receiving transmission oil and a fluid flow outlet fitting connected to said outermost shell for receiving transmission oil circulated through said cooler, the flow paths defined in part by said fittings communicating with said annular space at axially spaced locations, said turbulator construction registering with said shells and forming therebetween a helical flow path for the fluid flow that passes from one of said fittings to the other, said turbulator construction comprising two parts, the first part being a helical wire surrounding the innermost skill and engaging the adjacent shell surfaces to prevent crossflow from one point in the helical flow path to another in an axial direction, the geometric axis of the helical flow path formed by said turbulator construction the second turbulator construction being a turbulator ribbon having a plurality of undulations located between the helical wire and forming in said ribbon liquid flow openings, said ribbon being wrapped around the innermost shell in helical disposition whereby the flow path is generally helical and is characterized by localized turbulance. 